Schoolproject: building a cruiserbike

[UnDerzon3]

Does your design intent match your fabrication abilities?
Using 1.5" tubing for the chain/seat stays is problematic without some more design work.

why is that?

[c.p.odom]

Your concept sketch is a long ways from having a design. Cantilevered single stays are fine but it will be best if welded at two points and made from thick steel, your sketch allows for that. But from that point the stays will have to bend outward considerable to clear the tire and chain, they will also be rotated to give the desired curve that you show, as you rotate them they lose the inside curvature, this is where "Problematic" comes in. There are no dropouts shown in this sketch, you still have to keep the rear end around 110-120mm while having to deal with three inches of tubing width. fortunately crank clearance is not an issue with the bottom bracket being far forward.

[UnDerzon3]

Your concept sketch is a long ways from having a design. Cantilevered single stays are fine but it will be best if welded at two points and made from thick steel, your sketch allows for that. But from that point the stays will have to bend outward considerable to clear the tire and chain, they will also be rotated to give the desired curve that you show, as you rotate them they lose the inside curvature, this is where "Problematic" comes in. There are no dropouts shown in this sketch, you still have to keep the rear end around 110-120mm while having to deal with three inches of tubing width. fortunately crank clearance is not an issue with the bottom bracket being far forward.

ok now i feel like i have a little better understanding of what you're talking about. I've been thinking about the rear of the frame a lot, specially about that i will have to bend the stays so much outward. After all this thinking I've more or less decided to build something similar to what this sketch's showing just in order to be able to fit in the 120 mm wide reartire...
(which i maybe will change for a 160 mm tire instead ^^)

Hope you will be able to understand the sketch


// Rasmus

[c.p.odom]

This is doable, I would call it a workaround as it does not keep to your original design intent. Try to avoid adding that kind of angular fabrication to a design that is based on curves. Instead try using two short curved pieces of tubing or even better one U shaped tube that wraps around and the stays attach to it.

Now my personal opinion on the forks:
Do not use the common triple crown fork setup. I find them to be cheap and tacky wannabe copies of motorcycle parts. Your building a bicycle not a pedal powered motorcycle, keep the design DNA somewhat pure. It is OK to pull design ideas from many things in life but not to just copy them.
Curved frames NEED curved forks. Do not stray from the design intent just because it is easy to bolt something on.

To very loosely paraphrase Karl Von Clausewitz:
Just because something appears to be simple does not mean that it will be easy to do.

[UnDerzon3]

This is doable, I would call it a workaround as it does not keep to your original design intent. Try to avoid adding that kind of angular fabrication to a design that is based on curves. Instead try using two short curved pieces of tubing or even better one U shaped tube that wraps around and the stays attach to it.

Now my personal opinion on the forks:
Do not use the common triple crown fork setup. I find them to be cheap and tacky wannabe copies of motorcycle parts. Your building a bicycle not a pedal powered motorcycle, keep the design DNA somewhat pure. It is OK to pull design ideas from many things in life but not to just copy them.
Curved frames NEED curved forks. Do not stray from the design intent just because it is easy to bolt something on.

To very loosely paraphrase Karl Von Clausewitz:
Just because something appears to be simple does not mean that it will be easy to do.

We'll see how I will do with the forks. My nr one priority right now is to start building the frame and start looking a litte closer on what kind of rim i will be using for the reartire.
Still, thank you very much for your comments so far, they've been helpful. Hope you will follow my project

// Rasmus

[UnDerzon3]

here's a little update for you guys
sadly I didn't get any pipes for the frame today at school, my welding teacher hasn't order any yet -.-
anyway, i rebuilt the crank which i took from another bike. Hope the pictures talking for themself ^^

// Rasmus

[c.p.odom]

Nice job on the BB shell!
Is this HS, Jr College, or what?
There are not many ways to learn the "Trades" anymore.

[UnDerzon3]

Nice job on the BB shell!
Is this HS, Jr College, or what?
There are not many ways to learn the "Trades" anymore.

thanks! always fun to get some positive response
and It's high school

[wimpy]

Nice job. You're a lucky guy, 'cause you learned how to weld. It's always great, if you can build your own things. I'm a bit jealous. Keep up the good work !

[UnDerzon3]

Nice job. You're a lucky guy, 'cause you learned how to weld. It's always great, if you can build your own things. I'm a bit jealous. Keep up the good work !

thanks but it's a long way to go It's been really fun learning how to weld and absolutely not as hard as I thought it should be

[c.p.odom]

You making anymore progress?
Will this project languish at the end of the school year?
Come on old guys support the grommet!

[UnDerzon3]

You making anymore progress?
Will this project languish at the end of the school year?
Come on old guys support the grommet!

sadly i'm probably won't be able to make any progress until after the summer. Cuz my welding teacher haven't ordered any tubes for the frame and therefore i hadn't been able to start with the frame. I hope that he will get them til next week and that he lets me take them home so I can work on the bike over the summer, but we'll have to see about that.
I'm probably going to start working on the rearwheel soon and try to solve everything about that (which could take some time )
the project should be done by the end om the next school year so at least i got a lot of time to fulfill it.
once again, thanks for the support. Sry i've haven't done any further progress but it's not exactly my fault

// Rasmus

[UnDerzon3]

Hello guys i have some bad news for you
I wasn't able to get any tubes from school to take with me home over the summer so now i'm probably won't be able to start with the frame for a while.
I will keep searching for a motorcycle rim to have as the back wheel of my bike and i will keep you guys updated how it's going

that's all for now
// Rasmus

[c.p.odom]

Go source your own tubing, it's part of the learning curve.

[UnDerzon3]

Go source your own tubing, it's part of the learning curve.

yes i probably will but for now i will start with fixing a rearwheel, efter all i need that before i start the framework so i know how wide i need to build the swing

what do you guys think, is a 180mm wide motorcycle tire to wide for this bike?